This invention relates to microwave amplifiers, and more particularly to high power microwave amplifiers.
As is known in the art, microwave amplifiers have a wide variety of applications. In some of such applications, microwave signals must be amplified to relatively high power levels. One technique suggested to provide such high power amplification is to divide the signal to be amplified into a plurality of signal channels, each channel having an amplifier module. The outputs of the amplifier modules are then combined into a composite signal. The limit to such an approach however is dictated by power losses in the combining network and the requirement of properly phasing each of the amplifiers (i.e., transistors). In addition, isolation should be provided between modules so the effect of module failure on overall amplifier power will be minimized. In a practical case, such as at Ku-band, the output power of typical Microwave Monolithic Integrated Circuit (MMIC) chips providing the power amplifier modules are in the order of 10 Watts maximum. However, some applications require even higher output power.
In accordance with the invention, an amplifier is provided having an electrically conductive structure. The structure has a waveguide network disposed in an interior region thereof. The waveguide network has an input section and an output section. The conductive structure has an amplifier input port and amplifier output port formed in outer wall portions of such structure. The waveguide network also includes a plurality of amplifier module input ports disposed on an outer surface of the structure. The input port of the conductive structure is coupled to the amplifier module input ports through the input section of the network. The waveguide network further includes a plurality of amplifier module output ports disposed on said outer surface of the structure. The amplifier module output ports are coupled to the output port of the conductive structure through the output section of the network. Each one of the amplifier module output ports is associated with one of the plurality of amplifier module input ports. The amplifier includes a plurality of amplifier modules. Each one of the amplifier modules has an input and an output. The input and output ports of the conductive structure are coupled to a corresponding one of the amplifier input ports and the one of the amplifier output ports associated therewith, respectively.
In one embodiment, the waveguide network comprises a plurality of coupled magic tees.
With such an arrangement, the conductive structure may be mounted on a heat sink to enable removal of wasted heat.
In accordance with the invention, a microwave power amplifier is provided having a waveguide structure. The waveguide structure has formed therein a plurality of coupled waveguide magic tees. A first one of such magic tees has a port providing an input port for the amplifier. A second one of such magic tees has a port providing an output port for the power amplifier. A first portion of the magic tees includes the first one of the magic tees and provides a power divider. The power divider has a plurality of amplifier module input ports. The first portion of the magic tees divides power fed to the input port of the power amplifier to the plurality of amplifier module input ports. A second portion of the magic tees includes the second one of the magic tees and provides a power combiner. The power combiner has a plurality of amplifier module output ports. The second portion of the magic tees combines power at the plurality of amplifier module output ports at the output port of the power amplifier. The amplifier includes a plurality of amplifier modules each one having an input port coupled to a corresponding one of the plurality of amplifier module input ports and each one having an output port coupled to the plurality of amplifier module output ports.
In accordance with another feature of the invention, a microwave power amplifier is provided having a waveguide structure. The waveguide structure has formed therein a plurality of coupled waveguide magic tees. A magic tee has one input port and two output ports so that a signal to the input port is split evenly between the two output ports. A single magic tee can be used to feed an input signal to two amplifier module inputs, or a cascaded network of magic tees can be used to split an input signal xe2x80x9cNxe2x80x9d ways, where xe2x80x9cNxe2x80x9d is an integral power of 2, and feed xe2x80x9cNxe2x80x9d amplifier module inputs. Conversely, a magic tee can be used to combine the outputs of two amplifier modules into a common output port, and a network of magic tees can combine xe2x80x9cNxe2x80x9d modules.
In one embodiment, the waveguide structure has a pair of conductive blocks. Each one of the blocks has channels formed in a surface thereof. The channels in the pair of conductive blocks provide the plurality of coupled magic tees when the pair of blocks are connected together with the surface of one of the blocks facing the surface of the other one of the blocks.
In one embodiment, one of the pair of blocks has a pair of passages formed therein, such one of the passages extending from a pair of sidearms of one of the magic tees in the first portion thereof and terminating at a pair of apertures in an outer surface of one of the pair of blocks. The amplifier module input port of a corresponding one of the pair of the amplifier modules is disposed over, and coupled to, one of the pair of sidearms of a corresponding one of the magic tees in the first portion thereof through one of the pair of passages.
In one embodiment, the above-mentioned one of the pair of blocks has a second pair of passages formed therein. The second pair of passages extends from a pair of sidearms of one of the magic tees in the second portion thereof and terminates at a pair of second apertures in the outer surface of said one of the pair of blocks. The amplifier module output port of a corresponding one of the pair of the amplifier modules is disposed over, and coupled to, one of the pair of sidearms of a corresponding one of the magic tees in the second portion thereof through one of the second pair of passages.
In one embodiment, H-arms of the first and second portions of the magic tees are formed in a wall of the other one of the pair of blocks. A load is disposed in such one of the blocks at a terminating end of the H-arm.
In one embodiment, each one of the amplifier modules includes one, or more, MMIC chips. The module operates with microstrip transmission line mode energy. A waveguide-to-microstrip transition is provided for transitioning waveguide mode energy passing from the passage for the input port of such amplifier module into microstrip mode energy for the amplifier module.
In one embodiment, a microstrip-to-waveguide transition is provided for transitioning microstrip mode energy passing from the output of the amplifier module into waveguide mode energy to the passage fed by the amplifier module output.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.